Intraarticular, epidural, and intravenous analgesia after total knee arthroplasty

Background: After total knee arthroplasty, patients regularly suffer from s evere pain. It is unclear whether epidural or systemic pain therapy is supe rior in terms of postoperative pain relief, patients' comfort and side effe cts. A new therapeutic approach, intraarticular opioids, has been suggested with the detection of opioid receptors in inflamed tissue. This method has proven suitable for clinical use in small operations (e.g. knee arthroscop y). In this study, we compared epidural analgesia and intraarticular applic ation of morphine plus "on-demand" intravenous analgesia to "on-demand" int ravenous analgesia alone. Methods: Thirty-seven patients, scheduled for total knee arthroplasty, were randomly assigned to three treatment groups: in group 1 (EPI) patients rec eived bolus doses of morphine via an epidural catheter; in group 2 (IA) an intraarticular bolus of 1 mg of morphine was applied at the end of the oper ation with subsequent use of a patient-controlled analgesia (PCA) pump; gro up 3 (Control), in which only PCA was provided, served as control for both analgesic procedures. Main outcome measures included visual analogue pain s cales, total morphine consumption, and stress hormones. Results: No statistically significant differences in visual analogue pain s cales could be detected between the three groups. Application of intraartic ular morphine did not reduce the amount of analgesics required for postoper ative analgesia as compared to intravenous analgesia alone. Application of epidural morphine significantly suppressed beta-endorphine release, but did not significantly influence other stress hormones as compared to the contr ol group. Conclusion: Epidural and intravenous analgesia after total knee arthroplast y are equivalent methods of pain relief. In major orthopaedic procedures, a pplication of intraarticular morphine does not reduce analgesic requirement s.